The battle geometry that defines the civil war in Syria is one of the most convoluted in the world. Syrian army forces, moderate opposition factions, Salafist units, Al-Qaeda affiliates, Islamic State militants, Russian pilots, pro-Syrian Shia militias, Iranian Revolutionary Guard forces, Kurdish soldiers, and U.S. Special Operations Forces are all operating on the same land. Syria’s airspace is just as clogged as its soil; so many aircraft are flying in Syria’s airspace that the U.S. and Russia established a de-confliction channel to avoid a mid-air collision.

In fact, the news that U.S. aircraft struck pro-Syrian government militia forces outside of the southern Syrian town of al-Tanf is a perfect indictment of how confusing Syria’s battle space really is. According to a Pentagon statement, U.S. pilots engaged a convoy of pro-regime forces that breached a “no-go” area, where U.S. and British advisers are training anti-ISIS Syrian fighters. After appealing to Russia for assistance in grounding these units, U.S. jets buzzed the convoy and fired warning shots to demonstrate their intention. When none of that proved successful, airstrikes were ordered to stop the column in its tracks.

From a tactical point of view, U.S. forces were well within their rights to engage the pro-regime units. Whenever U.S. forces are deployed in a hostile environment, they have the power to use force if doing so is required to defend themselves. This is exactly what the U.S. military did in this specific situation—hostile forces were coming closer to a training base where U.S. special advisers were operating, and force was levied against the convoy only when it defied warnings to cease their advance.

And yet we would be ignoring the facts if we didn’t mention that the United States, for all intents and purposes, engaged in an armed action against a player in Syria’s civil war that Washington isn’t officially at war with.

The Assad regime and associated forces fighting in support of the Syrian government have never been included within the statutory authority U.S. policymakers are using to justify the military campaign against the Islamic State — an authorization for the use of force, by the way, that was passed more than 15 years ago and is stretched beyond rational, justifiable limits.

None of this is to make the case that what the U.S. military did was a violation of international or domestic law. Far from it; America’s men and women in uniform must be protected when operating in a dangerous environment. The lives of our soldiers, sailors, airmen, and marines come first.

What the airstrike in al-Tanf does illustrate is that an armed conflict— even one that is meticulously planned by expert strategists in the Defense Department—can quickly escalate into situations that the most experienced war planner may not anticipate. The old maxim that a war plan is rendered useless as soon as the first shots are fired is all too accurate.

The conflict in Syria is not like any other in the world today. Syria is no longer a country in the practical sense; it is a piece of the Middle East chessboard where the region’s major players like Saudi Arabia, Turkey, and Iran are fighting their own battles and using every last Syrian to do it. Besides fighting the Islamic State, the United States has no interest in picking winners and losers in a hybrid proxy and civil conflict powered by combatants content with continuing to slug it out.

It’s during times like these when restraint should outweigh all other considerations in the minds of policymakers across the national security bureaucracy. When the U.S. is operating within a conflict as muddied as Syria’s, the goals and military objectives need to be as clear as possible for our troops and advisers on the ground and our pilots in the air.

The legislative branch, the branch of government most directly related to the American people, also has a huge responsibility to ensure that our troops understand which enemy is fair game, which combatant should be avoided, and whether or not the entire country is solidly behind the mission. Unfortunately, with the exceptions of a few members of Congress who have worked diligently to force Congress to uphold its Article I, Section 8 responsibility– such as Reps. Walter Jones, John Garamendi and Sens. Rand Paul, Mike Lee, Tim Kaine, and Chris Murphy– America’s elected representatives have avoided the excruciatingly tough political debate that the Founders believed was required before sending the United States into a war.

It’s difficult for U.S. forces in the field to do their jobs when their elected officials are too timid, afraid, or uninterested in doing theirs.

So let the incident in al-Tanf serve as yet another lesson on the nature of war and the indispensability of congressional involvement in declaring or authorizing it. War is hard. It’s chaotic. But it’s even harder when the U.S. Congress is sitting on the bench.

Daniel DePetris is a fellow at Defense Priorities.

This piece was originally published by The Huffington Post on June 2, 2017. Read more HERE.